Senior Full-Stack App Reliability Review

Senior full-stack developer (TypeScript / React / Node / PostgreSQL) to review and tighten an existing field-service web app

About the project
JobStoq is a working web app for electrical contractors: it tracks material across the shop, service vans and jobs, and electricians use it on their phones in the field. It is live with a pilot company. Stack: TypeScript, React (Vite), Node/Express, PostgreSQL with Drizzle ORM, Clerk sign-in, pnpm monorepo, hosted on Replit. Code is on GitHub.

What I need
An experienced developer to make the app reliable, fast and polished:
- Fix bugs and phone layout problems (iPhone Safari especially)
- Review code changes before they go live
- Improve speed and data foundations over time
This is NOT a rebuild and NOT a native iOS/Android app. It's improving an existing web app.

How it starts: a small paid trial (fixed price, about 4–8 hours)
1. Read the codebase and send me a short plain-English review: the 5 biggest risks you see and what you'd fix first.
2. Fix one specific bug I'll give you, with a test, as a pull request on GitHub.
If the trial goes well, ongoing part-time work (a few hours a week).

Requirements
- 4+ years building production web apps with TypeScript, React, Node and PostgreSQL
- Has shipped an app that real people use every day (please link it or describe it)
- Based in Canada or a North American time zone; English communication
- Will sign an NDA and an IP agreement (all work belongs to the company)
- Comfortable explaining technical things to a non-technical founder (I'm an electrician)

To apply, answer these 2 questions in your bid (generic bids will be skipped):
1. Tell me about a production bug you tracked down in a React/Node/Postgres app. How did you find the cause?
2. How would you make sure a change to stock counts never loses or double-counts data?